JPH0792722A - Developer and developing device using the developer - Google Patents

Abstract

PURPOSE:To prevent liquid bridge phenomenon for obtaining excellent fluidity and a fine image by specifying the mean particle diameters of a hydrophobic inorganic oxide particle and a silicon particle which adhere to the surface of the particle of a developer containing polyester resin. CONSTITUTION:In this developer, a silicon particle 13 and a hydration-processed inorganic oxide particle 12 adhere about iniformly to the surface of a toner particle containing polyester resin and a coloring agent. The mean particle diameter of the inorganic oxide particle 12 is set up to be 1 to 20nm, and that of silicon particle 13 is set up to be 0.1 to 1.0mum. In addition, the silicon particle 13 is desirably to be contained at 0.05 to 3% in weight to the toner, and the inorganic oxide particle is desirably to be contained at 0.1 to 3% in weght to the toner. Thus, the lowering of charged quantity in a high temperature-humidity atmosphere, and liquid bridge phenomenon on a charge giving member or the surface of a photoreceptor can be prevented to obtain a fine image which has excellent fluidity and no image deterioration such as a fog on the image and the surface of the photoreceptor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used for forming an image by visualizing an electrostatic latent image and a developing device using the developer.

[0002]

2. Description of the Related Art In electrophotography, in general, an electrostatic latent image is formed on a photoconductor using a photoconductive substance, and then fine particles called toner are selectively formed on the obtained latent image. Then, the latent image is visualized by developing the latent image. An image is formed by transferring the visualized toner to a transfer material such as paper and then fixing the toner with heat and pressure or solvent vapor.

In developing an electrostatic image by electrophotography or the like, in order to form a visible image of good quality, the toner needs to have a high chargeability. Conventionally, a charge control agent (hereinafter CCA) is uniformly dispersed to provide the necessary charging property. Further, when a polyester resin is used as the binder resin, a sufficient negative charge can be obtained without using CCA, and when it is used in combination with CCA, a toner having a good rise of charge can be obtained even in a one-component developing method with a small charging probability. be able to.

However, when the binder resin, which is the main component of the toner particles, is polyester, the polyester resin has an ester bond in the main chain and polar groups such as hydroxyl group and carboxyl group at the terminals, so that the toner particles easily absorb moisture. , Due to a decrease in the amount of charge in a high temperature and high humidity atmosphere, and a liquid bridge phenomenon with the charging member or the surface of the photoreceptor,
There is a defect that image quality deterioration such as fog on the image and on the surface of the photoconductor is likely to occur.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a developer containing a polyester resin from lowering the charge amount in a high temperature and high humidity atmosphere, and to prevent a liquid bridge phenomenon between the charge imparting member or the surface of the photoreceptor. It is an object of the present invention to provide a developer having good fluidity and capable of obtaining a good image without image deterioration such as fogging on the image and on the surface of the photoreceptor.

Another object of the present invention is to use a developer containing a polyester resin to obtain a good image without the liquid bridge phenomenon and without image deterioration such as fog on the image and on the surface of the photoreceptor. To provide a developing device.

[0007]

The present invention has been made to solve the above conventional problems. The developer of the present invention comprises toner particles containing a polyester resin and a colorant, hydrophobized inorganic oxide particles having an average particle diameter of 1 to 20 nm, and an average particle diameter of 0.1 to 1.0 μm. And an external additive containing silicon particles.

The developing device of the present invention develops the electrostatic latent image by supplying a developer to the means for forming an electrostatic latent image on the image bearing member and the image bearing member on which the electrostatic latent image is formed. The developing agent comprises toner particles containing a polyester resin and a colorant, and hydrophobized inorganic oxide particles having an average particle diameter of 1 to 20 nm and 0.1 to 1.0.
and an external additive containing silicon particles having an average particle diameter of μm.

The amount of inorganic oxide particles added to the toner is preferably 0.1 to 3% by weight, and the amount of silicon particles added is preferably 0.05 to 3% by weight. As the silicon particles, polymethylsilsesquioxane is preferable.

[0010]

In the non-magnetic-component process, for example, the toner has less chance of charging as compared with the two-component developer using the carrier, so that the amount of charge is low. Therefore, if polyester is used as the resin that is the main component of the toner, the charge amount increases. However, on the other hand, fogging occurs on the image and the surface of the photoconductor in a high temperature and high humidity atmosphere. As a cause of this, since the polyester resin has a polar group, a moisture bridge is formed when the distance between the toner surfaces or the distance between the toner surface and the surface of the photosensitive member approaches a certain distance or less. This is the liquid bridge phenomenon. In order to eliminate this phenomenon, in the present invention, silicon particles are externally added to the toner.

The silicon particles have a large particle size,
It has a strong negative charge. On the other hand, since the flowability of the toner is deteriorated only by this, an inorganic oxide subjected to a hydrophobizing treatment can be externally added at the same time as the silicon particles in order to improve the flowability.

The external additive of the present invention is attached onto toner particles containing a polyester resin and a colorant. A schematic diagram showing an example of the developer of the present invention is shown in FIG. As shown in FIG. 1, the developer 25 of the present invention has a structure in which the silicon particles 13 and the hydrophobized inorganic fine particles 12 are substantially uniformly attached on the toner particles 11.

When an image is formed using such a developer, fog on the image and on the surface of the photoconductor is reduced, the fluidity of the toner is improved, and solid images, image density, fixability, and fine line reproducibility are obtained. Image characteristics are improved.

In the present invention, an excellent effect can be obtained by limiting the particle size of the silicon particles and the inorganic oxide to some extent. Furthermore, in the present invention, a very excellent effect can be obtained by limiting the contents of the silicon particles and the inorganic oxide.

The hydrophobized inorganic oxide particles used in the developer of the present invention have an average particle diameter of 1 to 20 nm. Also, the silicon particles are 0.1 to 1.0 μ
It has an average particle size of m. Further, the silicon particles are preferably contained in the toner in an amount of 0.05 to 3% by weight, and the inorganic oxide particles are preferably contained in the toner in an amount of 0.1 to 3% by weight.

On the other hand, the particle size of silicon particles is 0.1.
When it is less than μm, the effect of preventing the liquid bridge phenomenon and the effect of reducing the fog are small. On the other hand, if the particle size exceeds 1.0 μm, the fluidity of the toner is poor and cleaning failure occurs. If the addition amount of silicon particles is less than 0.05%, no effect is obtained, and if it exceeds 3%, the fluidity of the toner deteriorates. If the particle size of the inorganic oxide is less than 1 nm, the toner has good fluidity but poor fog. On the other hand, if it exceeds 20 nm, the fluidity becomes poor. If the addition amount of the inorganic oxide is less than 0.1%, the fluidity tends to be poor, and if it exceeds 3%, fog tends to occur.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples. First, the silicon particles used in the present invention, such as polymethylsilsesquioxane, can be produced, for example, as follows. Production Example of Polymethylsilsesquioxane A four-necked flask equipped with a thermometer, a reflux condenser and a stirrer was charged with 4,000 parts of water and 50 parts of 28% aqueous ammonia solution, and 100 r.p.m. p. After stirring for 10 minutes at m, a uniform aqueous ammonia solution was obtained. To this aqueous ammonia solution, methyltrimethoxysilane 600 of 10 ppm in terms of chlorine atom is converted.
Part is 5r. p. The mixture was quickly added so as not to mix with the aqueous ammonia solution while rotating the stirrer at m to obtain a two-layer solution of a methyltrimethoxysilane layer as the upper layer and an aqueous ammonia solution layer as the lower layer. Then, the stirring speed of the stirrer was 20 r.
p. The hydrolysis / condensation reaction was allowed to proceed at the interface between methyltrimethoxysilane and the aqueous ammonia solution while maintaining the two-layer state with m.

As the reaction proceeds, the reaction product gradually precipitates in the lower layer, the reaction product floats in the lower layer and becomes cloudy, and the upper methyltrimethoxysilane layer gradually thins and disappears in about 3 hours. Yes (confirmed visually). In addition, set the temperature to 50
Hold at -60 ° C and stir under the same conditions for 3 hours, then 2
Cooled to 5 ° C. Next, the precipitated product was filtered through a 100-mesh wire net, dehydrated by centrifugation to form a cake, and the cake layer was dried in a dryer at 200 ° C. This was crushed using a lab jet to obtain a white powder.

When the polymethylsilsesquioxane powder thus obtained was observed with an electron microscope, it was almost spherical with a particle diameter ratio of X-axis to Y-axis of 1.0 to 1.2. It was confirmed. The average particle size is about 0.
It was 5 μm.

The polymethylsilsesquioxane used in the present invention is preferably one obtained by hydrolyzing and condensing methyltrialkoxysilane or its hydrolysis / partial condensate in an aqueous solution of ammonia or amines. The polymethylsilsesquioxane thus obtained has almost no impurities such as chlorine atom, alkaline earth metal, and alkali metal, and has a spherical shape and excellent free-flowing property. In particular, it is preferable that the particles are substantially spherical and independent from each other from the viewpoint of fluidity.

The average particle diameter of the polymethylsilsesquioxane powder is preferably 0.1 to 1.0 μm. Such polymethylsilsesquioxane powder,
It has a strong negative charging characteristic. This polymethylsilsesquioxane powder is a titanium compound such as a silicon compound or tetrabutyl titanate such as organotrialkoxysilane or hexamethyldisilazane for the purpose of treating the hydroxyl groups remaining on the surface and adjusting the amount of negative charge. It is also possible to use a hydrolyzed / condensed product of which surface treatment has been carried out.

As the inorganic fine particles used in the present invention, for example, kaolin, quartz powder, mica powder, talc, clay and silicon dioxide can be used. The surface of the inorganic fine particles is subjected to a hydrophobizing treatment. The hydrophobizing treatment is carried out, for example, in the case of silicon dioxide, by using dimethyldichlorosilane to react with silanol groups on the surface of silicon dioxide. In addition to the above, silicone oil, octylsilane, trimethylsilyl group and the like can be used for the hydrophobic treatment.

Examples of the colorant used in the present invention include chrome dye, carbon black, nigrosine dye, aniline blue, quinoline yellow and DuPont oil red.

The production examples of the developer according to the present invention will be shown below. Examples 1 to 4, Comparative Examples 1 and 2 94 parts by weight of polyester resin, carbon black (M
A-600: 3 parts by weight of Mitsubishi Kasei Co., 2 parts by weight of PP wax (Viscole 660P: Sanyo Kasei Co., Ltd.), and 1 part by weight of a chrome dye (S-34: Orient Chemical Co., Ltd.) were prepared.

These were melt-kneaded, cooled, pulverized, and classified to obtain a developer having a particle size of about 5 to 20 μm and an average particle size of 11.0 μm. Using a juice mixer (A) at a ratio shown in Table 1 so that the total of the silicon dioxide powder (A) and the polymethylsilsesquioxane powder (B) would be 0.8% by weight based on the developer. And (B) were simultaneously crushed to be mixed and externally added to obtain 6 kinds of samples (Examples 1 to 4 and Comparative Examples 1 and 2).

The obtained developer is housed in a Faraday cage consisting of a metal cylinder whose one end is sealed with a wire mesh of 300 mesh, and a high pressure gas is blown from the other end to remove the development difference through the wire mesh. When the difference in contact charge amount was measured (blow-off method), the developer showed a clear negative charge.

Next, an image was formed using the obtained developer. The developing device used for image formation has the following structure. FIG. 2 is a schematic view showing an example of the developing device according to the present invention. As shown in FIG. 2, a developing device main body 100 (hereinafter, referred to as a main body 100) has a developer container 101 (hereinafter, referred to as a container 101) for storing a developer, and the inside of the container 101 is a non-contained container. A magnetic one-component developer 25 is stored. Further, in the container 101, a mixer 7 for stirring the developer 25 is provided so as to be rotatable in the arrow direction a. Further, the main body 1 is provided with three rotators rotatable in the direction of the arrow, that is, the photosensitive drum 1, the developing roller 2, and the developer supply roller 4, which are adjacent to each other. The photoconductor drum 1 has a rotary base 8 inside and a negatively chargeable organic photoconductor 10 on its surface. When the organic photoconductor 10 is irradiated with an original image as an optical signal by a laser, the photoconductor drum 1 is statically charged. It is an image carrier on which an electric latent image is formed. The photosensitive drum 1 is connected to the ground. Next to the photoconductor drum 1 is a developing roller 2 for forming a developer image by attaching a charged developer 25 onto the electrostatic latent image on the photoconductor drum 1. Developing roller 2
Is covered with a member having both conductivity and elasticity. Further, next to the developing roller 2, there is a developer supplying roller 4 for supplying the developer 25 contained in the container 101 onto the developing roller 2. Further, above the developing roller 2, a blade 15 having a function of restricting the amount of the developer 25 supplied to the developing roller 2 and at the same time frictionally charging the developer 25, and a blade holder 17 for supporting the blade 15 are provided. Is firmly attached. Further, the developing roller 2
A recovery blade 19 having a function of recovering the developer 25 not used for development from the developer 25 supplied to the developing roller 2 and returning the developer 25 into the container 101 is provided in the lower part of the. Below the photoconductor drum 1 is a transfer device 21 for moving the developer image formed on the photoconductor 10 onto the transfer material.

The developing process in the developing device having such a structure is as follows. First, the developer 25 in the container 101 is sent to the developer supply roller 4 while being stirred by the mixer 7. Next, the developer 25 forms a thin layer of the developer 25 on the surface of the supply roller 4. When forming a thin layer, the amount of developer supplied from the blade 15 to the developing roller 2 is regulated, and at the same time, the developer on the developing roller 2 is flattened by the blade 15. This causes triboelectric charging between the thin layer and the blade. The developer 25 is charged by this friction.

By the way, the surface of the negatively chargeable organic photoreceptor 10 on the photoreceptor drum 1 is uniformly charged to about -500 to -550 V by a charger (not shown).
When the original image is directly irradiated onto the charged organic photoconductor as a light image, the resistance of the organic photoconductor 10 in the irradiated part is lowered, the electrification of this part flows to the ground, and the surface potential approaches 0V. A latent image is formed. In the reversal development method in which the developer is adhered to the electrostatic latent image and the development is performed, a negatively chargeable developer is used as the developer.
Therefore, when the developing roller 2 having a thin layer of the negatively charged developer 25 on its surface and the photosensitive drum 1 are rotated in the opposite directions, the elastic force of the developing roller 2 causes the thin layer on the photosensitive member 10. Is slid on. The developer 5 is attached to the electrostatic latent image by the mechanical transport force and the electrostatic attraction force of the charges on the photoconductor and the charges of the developer, and the development is performed.

On the other hand, although not shown, the main body 101 includes
A paper supply tray for supplying paper is installed. The paper supplied from this tray is sent between the photoconductor drum 1 and the transfer device 21 as a transfer material for transferring the developer image formed by the development. When an electric charge having the same sign as the electric charge of the developer is applied to the back side of the fed paper by the transfer device, the developer image moves onto the paper by the force of the electric field. Further, the excess developer 25 that is not used for the development while being supplied to the developing roller 2 is
It is recovered again into the developing device via the recovery blade 19.

This developing device is set in the image forming device,
Image formation was performed. Furthermore, for these samples,
The fog, the fog on the drum, the solid followability, and the developer fluidity were evaluated. The results are shown in Table 1.

The evaluation methods are as follows. Measurement of fog The density of the white part of the obtained image at 3 points and the density of 3 points of the white background are measured, and the fog is obtained from the following formula: fog (%) = average density of white background-average density of white background of image.

If the obtained fog value is 0.50% or less, it is practical. Measurement of fog on the drum Take the toner on the photoconductor with mending tape and stick it on a blank paper. Stick a plain tape on the same blank paper and take a measurement sample. The density of 3 points of the tape with toner and 3 points of the tape on the white background are measured. The fog on the drum can be found from the above formula using the obtained density.

The numerical value of the obtained fog on the drum is 5.0.
% Or less, it is practical. Solid followability Use the full solid chart of the image formation test chart. The results of the measurement of the paper were evaluated as follows: ○: The entire surface was uniformly black ×: There were many black spots XX: Toner was not transferred to the paper on the way Developer fluidity 60 mesh, 100 mesh, 200 The three sieves of the mesh are overlapped and set on a powder tester to obtain a sample. Put the obtained material in the top mesh and vibrate for 30 minutes. After that, the toner remaining amount on each mesh is measured.

The measurement results were evaluated as follows: O: Total toner remaining amount of three meshes is less than 5.0 g X: Total toner remaining amount of three meshes is 5.0 g or more

[0036]

[Table 1]

[0037]

When the developer and the developing device of the present invention are used, even if the developer contains a polyester resin, the amount of charge is reduced in a high temperature and high humidity atmosphere, and the liquid bridges with the charging member or the surface of the photoreceptor. Since the phenomenon does not occur, it is possible to obtain a good image without image deterioration such as fogging on the image and on the surface of the photoconductor.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a developer of the present invention.

FIG. 2 is a schematic view showing an example of a developing device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Development roller 4 ... Developer supply roller 7 ... Mixer 8 ... Rotation base 10 ... Organic photoconductor 11 ... Developer particles 12 ... Inorganic fine particles 13 ... Silicon particles 15 ... Blade 19 ... Recovery blade 25 ... Development Agent 100 ... Main body 101 ... Container

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Claims (4)

[Claims] 1. Toner particles containing a polyester resin and a colorant, and hydrophobized inorganic oxide particles having an average particle diameter of 1 to 20 nm and attached to the surface of the toner particles, and 0.1 to 1 An external additive containing silicon particles having an average particle diameter of 0.0 μm. 2. The silicon particles are used for a developer,
The developer according to claim 1, wherein the content of the inorganic oxide is 0.05 to 3% by weight, and the content of the inorganic oxide is 0.1 to 3% by weight with respect to the developer. 3. The developer according to claim 1, wherein the silicon particles consist essentially of polymethylsilsesquioxane. 4. A means for forming an electrostatic latent image on an image carrier,
A means for supplying a developer to the image bearing member on which the electrostatic latent image is formed to develop the electrostatic latent image is provided, wherein the developer is toner particles containing a polyester resin and a colorant, and 1 to 20 nm. And an external additive containing the hydrophobized inorganic oxide particles having an average particle size of 1. and an external additive containing silicon particles having an average particle size of 0.1 to 1.0 μm.